For regional anesthesia, a cathether such as an epidural catheter is used to introduce anesthetic agents to the nerves for example at the spine of a patient. To place a catheter close to the nerve spinal column, an epidural needle such as a Tuohy needle is used by the anaesthesiologist. The Tuohy needle is inserted into the nerve sheath, alongside a nerve plexus of the patient. The Tuohy needle has a sharp distal end that has a beveled aperture, the sharp distal end adapted to readily pierce the nerve sheath at the spinal column of the patient. Once the anaesthesiologist believes that she has placed the epidural needle at the appropriate location in the patient, she would insert the catheter into the needle and move the catheter until its distal end extends out from the beveled end of the needle cannula. The catheter is usually marked along its length so that the anaesthesiologist knows approximately how much the distal end of the catheter extends beyond the distal tip of the needle cannula. The direction in which the catheter is moved inside the patient depends, to a large extent, on the insertion and placement of the needle cannula inside the patient by the anaesthesiologist and the skill of anaesthesiologist in maneuvering the catheter. Oftentimes, an anaesthesiologist, experienced or not, may have a difficult time maneuvering the distal end of the catheter to the desired location. As a result, a larger than necessary dose of anesthetic agent may be required to be delivered to the patient to locally anaesthetize the patient.
There is therefore a need to provide a catheter that can readily be maneuvered by the physician to a desired location inside a patient.
SUMMARY OF THE PRESENT INVENTION
To assist a physician or an anaesthesiologist with the placement of a catheter for supplying local anesthetic to a patient, the catheter of the instant invention has at a portion proximate to its distal end, whereby anesthetic agent is output to a patient, a cross-sectional profile that predefines or predisposes the distal end of the catheter to be bent or headed to a given direction, once the catheter is no longer constrained by the guide or needle cannula wherethrough it passes. Conventionally, a catheter usually has a uniform circular cross sectional configuration throughout. For the instant invention, at least one portion of the catheter, preferably at a distance proximate to the distal end of the catheter, is configured to have a cross-section, which may or may not be circular, that predefines or predisposes the distal end of the catheter to move in a given direction. One of the cross-sectional profiles that may be used is an oval shaped configuration that causes, or predisposes, the catheter to be bent in the direction of the width of the greater cross-section width. Another sectional profile that may be used at the one portion of the catheter is C-shaped so that the distal end of the catheter is predisposed to bend toward the direction represented by the open mouth of the C.
In addition to having different cross-sectional profiles, the one portion that is configured to cause the distal end of the catheter to bend at a distal direction could have a different thickness at a section thereof so that, even though from the outside diameter the catheter may appear to be no different from the rest of the catheter, the inside diameter at the one portion is dimensioned to have thicker and thinner sections so that, once the one portion is outside of the needle cannula or guide, subject to additional movement, the catheter would tend to bend at a predefined orientation to a given direction, thereby enhancing the movement of the distal end of the catheter inside the patient.
The instant invention therefore relates to a catheter to be used with and passable through a guide for insertion to a patient. The catheter includes a tubing that has at least one portion having a cross-sectional profile that is configured to bend or orient the tubing in a given direction so that when the one portion of the tubing extends out of the guide, the tubing is predisposed to be routed or headed in a given direction.
The instant invention also relates to a combination of a hollow guide and a catheter passably fitted to and moveable along the guide. The catheter has a substantially circular cross-sectional profile along its entire length except for at least one portion between its distal and proximal ends. This one portion has a cross-sectional profile configured to predispose the distal end of the catheter toward a given direction so as to cause the catheter to move toward the given direction once the one portion of the catheter is no longer constrained by the guide.
The instant invention further relates to a catheter that has a distal portion connected to a main portion by a junction that has a cross-section that is different from the respective cross-sections of the main and distal portions. The distal portion, if unguided, points to and is movable along a first direction; and the main portion, if unguided, would point to and is movable along a second direction not in alignment with the first direction. The catheter is insertable into and movable along a hollow guide extending along a given axis. The junction that connects the distal portion with the main portion is configured to have a cross-sectional profile that causes the distal portion to bend or head toward the first direction once the distal portion and the junction are no longer confined within the guide after the catheter has been inserted to the guide and moved therealong.
The instant invention yet further relates to an apparatus that comprises a needle cannula and a regional anesthesia catheter such as an epidural catheter having a distal end and a proximal end. The catheter is movably fitted to the cannula with its distal end being inserted first into the first end of the cannula so that the catheter is movable along the cannula. The catheter has a substantially circular cross-section along its entire length except for at least one portion proximate to its distal end. This one portion has a non-circular cross-section configured to cause the distal end of the catheter to move in a direction predefined by the configuration of the one portion when the distal end and then the one portion of the catheter exit outside the cannula through its distal end.
The instant invention moreover relates to a method for introducing a catheter into a patient in which a hollow cannula is provided. The catheter has at least one portion between its distal and proximal ends that is configured to cause the distal end of the catheter to be predisposably moved toward a direction not in alignment with the cannula when the one portion is not confined within or constrained by the cannula. The cannula is inserted into the patient proximate to a location where anesthesia is desired. A catheter is inserted into and moved along the cannula. The distal end of the catheter is first inserted into the cannula. Thereafter, the catheter is continuously moved into the cannula until at least the one portion of the catheter is extended beyond the distal end of the cannula to predisposedly move the distal end of the catheter to the desired placement within the patient.
Another embodiment of the instant invention features a catheter such as for example a regional anesthesia catheter that has a cross sectional profile that extends longitudinally along the entire length of the catheter. The cross sectional profile is configured to cause the catheter to move in a predefined direction. In particular, the catheter of this embodiment comprises a tubing passable through a guide for insertion into a patient, the tubing having a given length and the cross sectional profile of the tubing along its entire length is configured to cause the catheter to bend, curve or move in a given direction.
The cross sectional profile of the catheter of the instant invention at the one portion as noted above or along the entire length of the catheter may be configured to be oval shaped or C shaped, or other non-circular shapes for example. The cross sectional profile may also be configured to be partially concaved inwards toward the center axis of the catheter or tubing, or may have a section of the wall where its thickness is different from that of the rest of the catheter.
It is therefore an objective of the instant invention to provide a catheter that is configured to be moved in a predisposed direction inside the patient.